Go to the mods section and download Ferrarimans unofficial championship creator.
It will automatically create an aos file for you, which is the same as an rfm file. You can then edit that instead so at least you can create your seasons.

If I remember, you have to edit the config file to put the right location for your GSC folder.
If it still doesn't work, check the properties of the shortcut that came with the season creator, I think it has ferrariman's hard drive location in there so it wont work till you correct it. At least, it was something along those lines. If you still have problems, I'll take a look when I'm next at my game pc.

I downloaded the champ creator, which worked firt time, but I still have a problem with picking up the correct talent files, e.g. Caca Bueno has two talent files - one for StockCar and one for F3 or Kart (can't remember which).

I've created a season for stock cars and noticed the wrong talent file is being selected. Normally, I would more fully qualify the pathname in the .rfm file DriversDir=GAMEDATA\TALENT\StockV8\ to ensure a specific mod always picked up the correct files, but as the .rfm files are encrypted I can't do this.

I tried to add the above path to the championship file created, but this doesn't seem to get recognised. The only option I can see is to change the names for the respective .veh files for each mod and change the talent files to match.

First, make sure the config file in the custom championship creator folder is set to your main GSC folder

Second, when you have unzipped the championship creator file, go into that folder and right click on the Championship Creator shortcut. Click on properties.
Make sure the target path is correct for the creator program.
Make sure the Start in line is also correct for the creator program.